Alzheimer's disease (AD) is the most common neurodegenerative disorder and the leading cause of dementia in the elderly. Although the genetic defects underlying several familial forms of AD have been identified, the etiology of late-onset AD?the sporadic form which accounts for the vast majority of AD cases?remains unknown. The lack of effective means of prevention or disease-modifying treatment for AD and the failure of recent clinical trials emphasize the needs to better understand AD pathogenesis and to identify novel therapeutic targets. The goal of this project is to use large-scale, unbiased, integrative proteomics, glycoproteomics, and glycomics approaches to discover novel disease processes in sporadic AD and identify new targets for early diagnosis and therapeutic intervention. Protein glycosylation is one of the most common posttranslational modifications, and it is estimated that over 50% of all proteins are glycosylated. Glycosylation is also one of the most diverse and complicated posttranslational modifications, encompassing a broad array of modifications involving covalent linkage of complex carbohydrates (glycans) to specific amino-acid residues of proteins. Ample evidence indicates that protein glycosylation plays crucial roles in many biological processes, including cell stress response, vesicular trafficking, protein quality control, signal transduction, and intercellular communication. Furthermore, altered glycosylation has been implicated in a number of brain diseases, including AD. However, very little is currently known about human brain glycoproteome and glycome and their changes in AD. In this project, the research team will establish an innovative, high-throughput, multiplex platform that uses a combination of label-free quantitative proteomics and latest glycoproteomics and glycomics technologies for high-resolution, comprehensive analyses of total proteins, glycoproteins, and glycans in human clinical specimens. The proposed research will use this multiplex platform to determine AD-associated changes in the brain proteome, glycoproteome, and glycome and discover novel molecular pathways in AD pathogenesis. Furthermore, this project will use the multiplex platform to profile the proteome, glycoproteome, and glycome in human AD and control cerebrospinal fluid, blood plasma and serum samples to identify novel biomarkers for early diagnosis and monitoring disease progression. Successful completion of this project will advance our understanding of AD pathogenesis and provide novel targets for AD treatment.